Catheter with deformable distal electrode

ABSTRACT

A catheter probe configured with a capability to present a larger tissue contact area or “footprint” for larger, deeper lesions, without increasing the french size of the catheter, especially its distal section, includes an elastically deformable electrode configured to adopt a neutral configuration and a tissue contact configuration. The deformable electrode comprising a hollow porous tube with a distal portion having a closed distal end, and a proximal portion defining an opening to an interior of the tube, where the distal tip end is received in the tube through the opening and the distal section is generally surrounded by tube, with the proximal portion being affixed to an outer surface of the distal section. In some embodiments, the closed distal end is shaped with a bulbous portion that can spread and widen to provide a larger surface contact area.

FIELD OF INVENTION

This invention relates to electrophysiologic (EP) catheters, inparticular, deflectable EP catheters for RF ablation.

BACKGROUND

Electrode catheters have been in common use in medical practice for manyyears. They are used to stimulate and map electrical activity in theheart and to ablate sites of aberrant electrical activity.

In use, the electrode catheter is inserted into a major vein or artery,e.g., femoral vein, and then guided into the chamber of the heart whichis of concern. In some medical procedures, energy is imparted to bodytissue locally, in a concentrated dose, and it is desirable to cool thetreatment area in order to reduce collateral tissue damage. For example,cardiac ablation therapy is used to treat arrhythmias by heating tissuewith radio-frequency (RF) electrical energy to create non-conductinglesions in the myocardium. It has been found that cooling the area ofthe ablation site reduces tissue charring and thrombus formation.Catheters with irrigated distal tips are known as part of integratedablation system. Typically, a metal catheter tip, which is energizedwith RF current to ablate the tissue, has a number of irrigation holes,distributed circumferentially around the tip, for irrigation of thetreatment site. A pump coupled to the catheter delivers saline solutionto the catheter tip, and the solution flows out through the holes duringthe procedure in order to cool the catheter tip and the tissue.

In certain regions of the heart, for example, in the ventricles wheretissue is thicker, the creation of transmural lesions can bechallenging. Deep lesions typically require higher RF energy but higherRF energy can lead to undesirable steam pops. Thus, there is a desire tocreate deeper lesions by increasing electrode/tissue contact area butwithout increasing the size of the catheter itself.

Catheters with flexible tips are known. U.S. Pat. No. 5,720,719describes a catheter having a probe end that includes a malleable tubeand a flexible tube. U.S. Patent Publication No. 2014/0121657, whosedisclosure is incorporated herein by reference, describes a medicalprobe having a deformable distal end that includes a flexible and porousmaterial. The flexible and porous material may include a conductivematerial. An electrical conductor can be coupled to the flexible andporous material so as to convey RF energy to the deformable distal end,and the RF energy can be conveyed to tissue by the deformable distal endconveying the RF energy to the tissue. The medical probe may includemeans for inflating the deformable end which may include conveying afluid that irrigates the tissue through pores of the deformable distalend. The means for inflating the deformable distal end may includeconveying the fluid the fluid so as to generate a mechanical forcesufficient to inflate the deformable distal end. A contact area betweenthe deformable distal and the tissue can increase upon pressing thedeformable distal end against the tissue.

U.S. Pat. No. 8,249,685 is directed to an apparatus for mapping and/orablating tissue that includes a braided conductive member that may beinverted to provide a ring shaped surface. When a distal tip of thebraided conductive member is retracted within the braided conducivemember, the lack of protrusion allows the ring-shaped surface to contacta tissue wall such as a cardiac wall. In an undeployed configuration,the braided conductive member is longitudinally extended, and in adeployed configuration, the distal end of the braided conductive memberis retracted to invert the braided conductive member.

The descriptive above is presented as a general overview of related artin this field and should be not be construed as an admission that any ofthe information it contains constitutes prior art against the presentpatent application.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter probe configured with acapability to present a larger tissue contact area or “footprint” forlarger, deeper lesions, without increasing the french size of thecatheter, especially its distal section. In some embodiments, thecatheter probe includes a flexible elongated shaft and a distal sectionhaving a distal tip end, and an elastically deformable electrodeconfigured to adopt a neutral configuration and a tissue contactconfiguration. The deformable electrode comprising a hollow porous tubewith a distal portion having a closed distal end, and a proximal portiondefining an opening to an interior of the tube, where the distal tip endis received in the tube through the opening and the distal section isgenerally surrounded by tube, with the proximal portion being affixed toan outer surface of the distal section. Advantageously, the closeddistal end of the tube is spaced apart from the distal tip end so as toallow the distal portion to deform and expand to provide a larger tissuecontact area.

In some embodiments, the distal portion has a preshaped bulbousconfiguration.

In some embodiments, the preshaped bulbous configuration has acontinuous curvature.

In some embodiments, distal portion of the tube has a greater width thatis at least about 1.5 times to 3 times or more greater than the width ofthe proximal portion.

In some embodiments, the tube is porous.

In some embodiments, the tube is constructed of a woven material.

In some embodiments, the tube is constructed of woven, electricallyconducting fibers.

In some embodiments, the tube is constructed of a biocompatibleelastomeric material.

In some embodiments, the tube is constructed of anelectrically-conductive material in conductive connection with an RF tipelectrode.

In some embodiments, the catheter probe includes a coupling memberbetween the distal section and the elongated shaft. In more detailedembodiments, the coupling member includes a tubular member configured asa spring joint, wherein the spring joint is configured to be responsiveto axial and angular forces acting on the distal section.

In other embodiments, a catheter probe of the present invention includesa flexible elongated shaft and a distal section having a distal tipelectrode, and an elastically deformable tube of woven fibers, whereinthe deformable tube is configured to adopt (i) a neutral configurationhaving a preformed bulbous portion with a first width and (ii) a tissuecontact configuration wherein the bulbous portion deforms into a secondwidth greater than the first width.

In some embodiments, the bulbous portion is free from contact with thedistal tip electrode when the deformable tube is in the neutralconfiguration, and the bulbous portion is in contact with the distal tipelectrode when the deformable tube is in the tissue contactconfiguration,

In some embodiments, the deformable tube has a closed distal endcomprising converging fibers and an open end defining an openingreceiving the distal tip electrode, and

In some embodiments, the deformable tube is electrically connected to anablation energy source

In some embodiments, the bulbous portion has a continuous curvature whenthe deformable tube is in the neutral configuration and the tissuecontact configuration.

In some embodiments, the catheter probe includes a coupling memberbetween the distal section and the elongated shaft, where the couplingmember is configured to be responsive to axial and angular forces actingon the distal section.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic, pictorial illustration of a catheter probeablating system, according to an embodiment of the present invention.

FIG. 2A is a side view of a catheter probe, including a distal sectionwith a deformable electrode, according an embodiment of the presentinvention.

FIG. 2B is a side view of a distal section with a tube and distal tipelectrode during assembly.

FIG. 2C is a side view of the catheter probe of FIG. 2A, wherein thedeformable electrode is in contact with tissue.

FIG. 3 is a schematic illustration of a force sensing subsystem and aposition sensing subsystem, according to an embodiment of the presentinvention.

FIG. 4 is a side cross-sectional view of a distal tip electrode,according to an embodiment of the present invention.

FIG. 5A is a side view of a tube for constructing a deformableelectrode, according to an embodiment of the present invention.

FIG. 5B is a side view of the tube of FIG. 5A, having been inverted, andbeing assembled with a distal tip electrode.

FIG. 5C is a side view of the assembled tube and distal tip electrode ofFIG. 5B, wherein the deformable electrode is in contact with tissue.

FIG. 6 is a side view of a catheter probe, including a distal sectionwith a deformable electrode, according to another embodiment of thepresent invention.

FIG. 7 is a schematic illustration of a positive displacement dispensingsystem, as used in the present invention, according to one embodiment.

FIG. 8A is a side view of a catheter probe, including a balloon member,according to another embodiment of the present invention.

FIG. 8B is an end view of the catheter probe of FIG. 8A.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to FIG. 1, which is a schematic, pictorialillustration of a catheter probe ablating system 10, and to FIG. 2Awhich illustrates a distal section 12 of a catheter probe 14 used in thesystem, according to embodiments of the present invention. In system 10,probe 14 comprises an elongated shaft 15 supporting the distal section12 and the distal section 12 and a portion of the shaft 15 are insertedinto a vasculature of a subject 22, for example, a chamber of a heart20. The probe is used by an operator 24 of system 10, during a procedurewhich typically includes performing ablation of body tissue 26. Thedistal section 12 advantageously includes a deformable electrode 40.

In some embodiments, for example, for intracardiac procedure, the shaft15 and the distal section 12 have a very small outer diameter, typicallyof the order of 2-3 mm. Therefore, all of the internal components ofcatheter probe 14, are also made as small and thin as possible and arearranged so as to, as much as possible, avoid damage due to smallmechanical strains.

As shown in FIG. 1, the functioning of system 10 is managed by a systemcontroller 30, comprising a processing unit 32 communicating with amemory 34, wherein is stored software for operation of system 10. Insome embodiments, the controller 30 is a computer comprising aprocessing unit, and at least some of the functions of the controllermay be performed using custom-designed hardware and software, such as anapplication specific integrated circuit (ASIC) or a field programmablegate array (FPGA). Controller 30 is typically managed by operator 24using a pointing device 36 and a graphic user interface (GUI) 38, whichenable the operator to set parameters of system 10. GUI 38 typicallyalso displays results of the procedure to the operator.

The software in memory 34 may be downloaded to the controller 30 inelectronic form, over a network, for example. Alternatively oradditionally, the software may be provided on non-transitory tangiblemedia, such as optical, magnetic, or electronic storage media.

In some embodiments, the controller 30 comprises a force module 48, anRF ablation module 50, an irrigation module 52, and a position module54. Processing unit 32 uses the force module to generate and measuresignals supplied to, and received from, a force sensor 58 in distal end12 in order to measure the magnitude and direction of the force on thedistal end. The operation and construction of force sensor 58 isdescribed in more detail below.

Processing unit 32 uses the RF ablation module 50 to monitor and controlablation parameters such as the level of ablation power applied viaelectrode(s) on the distal section 12. The ablation module also monitorsand controls the duration of the ablation that is provided.

Typically, during ablation, heat is generated in ablation electrodes, aswell as in the surrounding region. In order to dissipate the heat and toimprove the efficiency of the ablation process, system 10 suppliesirrigation fluid to distal end 12. System 10 uses irrigation module 52to monitor and control irrigation parameters, such as the rate of flowand the temperature of the irrigation fluid, as is described in moredetail below.

Processing unit 32 uses position module 54 to monitor the location andorientation of the distal section relative to patient 22. The monitoringmay be implemented by any tracking method known in the art, such as oneprovided in the Carto3® system available from Biosense Webster ofDiamond Bar, Calif. Such a system uses radio-frequency (RF) magnetictransmitter and receiver elements external to patient 22 and withindistal end 12. Alternatively or additionally, the position and trackingmay be implemented by measuring impedances between one or more sensingelectrodes 17 on the catheter probe 14, and patch electrodes 18 attachedto the skin of patient 22, such as is also provided in the Carto3®system.

As shown in FIG. 2A, distal section 12 is connected to the elongatedshaft 15. The distal section includes the force sensor 58. Aspects of aforce sensor similar to force sensor 58 are described in U.S. Pat. No.8,357,152, issued on Jan. 22, 2013 to Govari et al., entitled CATHETERWITH PRESSURE SENSING, and in U.S. Patent Publication No. 2011/0130648,to Beeckler et al., filed Nov. 30, 2009, entitled CATHETER WITH PRESSUREMEASURING TIP, both of whose disclosures are incorporated herein byreference.

FIG. 2A shows a side view of force sensor 58. Sensor 58 comprises aresilient coupling member 60, which forms a spring joint 62. In someembodiments, the coupling member 60 has a hollow tubular form with acentral lumen 68 therethough. Although there is no necessity thatcoupling member 60 be formed of two parts or longitudinal halves, thetwo part implementation simplifies assembly of elements comprised in theforce sensor, as well as of other elements mounted in the distal section12, into the member 60. Typically, coupling member 60 is formed of asuperelastic alloy, such as nickel titanium (Nitinol).

Coupling member 60 typically has one or more helices cut or otherwiseformed in the member, so that the member behaves as a spring. In anembodiment described herein, and illustrated in FIG. 2, helices areformed as two intertwined helices, a first cut helix 72 and a second cuthelix 74, which are also referred to herein as a double helix. However,coupling member 60 may have any positive integral number of helices, andthose having ordinary skill in the art will be able to adapt the presentdescription without undue experimentation to encompass numbers ofhelices other than two. Alternatively, the coupling member may comprisea coil spring or any other suitable sort of resilient component withsimilar flexibility and strength characteristics to those generated bythe one or more tubular helical cuts, referred to above.

Coupling member 60 is mounted within and covered by sheath 46 (shown astransparent), which is typically formed from flexible plastic material.Coupling member 60 typically has an outer diameter that is approximatelyequal to the inner diameter of sheath 46. Such a configuration, havingthe outer diameter of the coupling member to be as large as possible,increases the sensitivity of force sensor 58. In addition, and asexplained below, the relatively large diameter of the tubular couplingmember, and its relatively thin walls, provide a more spacious lumen 68enclosed within the coupling member which is used by other elements,described below, in the distal end. The sheath 46 extends the length ofthe coupling member 60 to provide a fluid tight seal around the hollowtubular form. The sheath 46 may be constructed of any suitablebiocompatible material that is flexible and insulating, includingCELCON, TEFLON or heat-resistant polyurethane.

When catheter probe 14 is used, for example, in ablating endocardialtissue by delivering RF electrical energy through electrode(s) on thedistal section 12, considerable heat is generated in the area of distalend 12. For this reason, it is desirable that sheath 46 comprises aheat-resistant plastic material, such as polyurethane, whose shape andelasticity are not substantially affected by exposure to the heat.

As shown in FIG. 2A and FIG. 3, within force sensor 58, typically withinthe central lumen 68 of the coupling member 60, a joint sensingassembly, comprising coils 76, 78, 80 and 82, provides accurate readingof any dimensional change in joint 62, including axial displacement andangular deflection of the joint, such was when the distal section 12 isadvanced into contact with tissue. These coils are one type of magnetictransducer that may be used in embodiments of the present invention. A“magnetic transducer,” in the context of the present patent applicationand in the claims, means a device that generates a magnetic field inresponse to an applied electrical current and/or outputs an electricalsignal in response to an applied magnetic field. Although theembodiments described herein use coils as magnetic transducers, othertypes of magnetic transducers may be used in alternative embodiments, aswill be apparent to those skilled in the art.

The coils in the sensing assembly are divided between two subassemblieson opposite axial sides of joint 62. One subassembly comprises coil 82,which is driven by a current, via a cable (not shown) from controller 30and force module 48, to generate a magnetic field. This field isreceived by a second subassembly, comprising coils 76, 78 and 80, whichare located in a section of the distal section 12 that is spaced axiallyapart from coil 82 across the spring joint 62. The term “axial,” as usedin the context of the present patent application and in the claims,refers to the direction of a longitudinal axis of symmetry 84 of distalend 12. An axial plane is a plane perpendicular to this longitudinalaxis, and an axial section is a portion of the catheter containedbetween two axial planes. Coil 82 typically has an axis of symmetrygenerally parallel to and coincident with axis 84.

Coils 76, 78 and 80 are fixed in distal end 12 at different radiallocations. (The term “radial” refers to coordinates relative to the axis84.) Specifically, in this embodiment, coils 76, 78 and 80 are alllocated in the same axial plane at different azimuthal angles about thecatheter axis, and have respective axes of symmetry generally parallelto axis 84. For example, the three coils may be spaced azimuthally 120degrees apart at the same radial distance from the axis.

Coils 76, 78 and 80 generate electrical signals in response to themagnetic field transmitted by coil 82. These signals are conveyed by acable 57 (FIG. 2A) extending from the distal section 12, and through theshaft 15 and a control handle 16 to controller 30 which uses forcemodule 48 to process the signals in order to measure the displacement ofjoint 62 parallel to axis 84, as well as to measure the angulardeflection of the joint from the axis. From the measured displacementand deflection, controller 30 is able to evaluate, typically using apreviously determined calibration table stored in force module 48, amagnitude and a direction of the force on joint 62.

Controller 30 uses position module 54 to measure the location andorientation of distal end 12. The method of measurement may be by anyconvenient process known in the art. In one embodiment, magnetic fieldsgenerated external to patient 22 create electric signals in elements inthe distal section 12, and controller 30 uses the electric signal levelsto determine the distal section location and orientation. Alternatively,the magnetic fields may be generated in the distal section 12, and theelectrical signals created by the fields may be measured external topatient 22. The elements in distal section 12 that are used to locatethe distal section 12 include coils 85 and 86 (FIG. 3) and one of thecoil 76, 78 and 80 (in addition to their use as elements of force sensor58) as orthogonal (x, y, z) position elements housed in the distalsection 12.

As shown in FIG. 2A, at or near a distal end of the sheath 46, a ringelectrode 17 is mounted on an outer surface of the sheath 46. At or neara distal end of the sheath 46, a distal tip member or electrode 21 has ashell wall 23 and a plug member 28, as shown in FIG. 4. The shell wall23 has an opening 25 and an interior cavity 27. The plug member 28 hasan interference fit with the shell wall in the opening 25 thus sealingthe interior cavity 27. The plug member 28 has at least one axialthrough-hole 29 receiving a distal end of an irrigation tubing 31 fortransporting fluid (e.g., saline) from a remote source via a luer hub 33(FIG. 1) that is in communication with a proximal end of the irrigationtubing 31 at or near the control handle 16. Fluid that is delivered intothe interior cavity 27 of the distal tip electrode 21 can cool theelectrode 21 before exiting the interior cavity 27 via irrigationapertures 35 formed in the shell wall 23 to outside of the electrode 21to flush and/or cool surrounding tissue.

The distal tip shell wall 23 and the plug member 28 are constructed ofelectrically conducting material, for example, platinum, gold, orstainless steel and, in some embodiments, is preferably made of aplatinum-iridium alloy (90% platinum/10% iridium). The plug member 28may be configured with one or more blind holes on its proximal face forreceiving one or more components, for example, a distal end of a leadwire 37 for energizing the plug member 28. Proximal of the plug member28 and distal of the spring joint 62, the coil 82 (FIG. 3) of the forcesensing subassembly may be housed in the sheath 46, within the lumen 68of the coupling member 60. The lead wire 37 and the irrigation tubing 31pass through a protective tubing 65 that extends through the lumen 68and further through a lumen of the catheter shaft 15.

FIG. 5A illustrates a woven material suitable for construction of thedeformable electrode 40 of the distal section 12. For some applications,a resilient, woven fabric or woven mesh may be advantageous. Forenhanced mechanical strength and resilience, the woven material may bewoven at least partially from elastic metal fibers, such as strands ofNitinol. The use of a metal-based fabric is also helpful in conductingelectrical energy to the intracardiac tissue.

In some embodiments, the material includes interwoven fibers 41 that areformed as a hollow tube 42, as shown in FIG. 5A, with an outer surface51 and an inner surface 52 defining a passage 43 between a proximal openend 44, a distal closed end 45 where distal free ends of the fibers 41are gathered to converge and bunched together into a nub 47, forexample, by a other fibers, a fastener, and/or adhesive, to close offthe passage 43. With the nub 47 being outside of the passage 43 andpointing distally, as shown in FIG. 5A, the tube 42 is turned inside outand inverted such that the nub 47 is brought in the passage 43 andpoints proximally, and the inner surface 52 faces outwardly to present asmooth and atraumatic distal end surface, as shown in FIG. 5B. The tube42 is then slipped onto or otherwise mounted over the distal section 12with a distal tip end 13 being inserted through the proximal open end44. The distal section 12 is advanced to a location X that is proximalof the distal closed end 45 of the tube 42 such that there is volumespace gap S between the distal closed end 45 of the tube 42 and distaltip end 13 of the distal section 12, when the tube 42 is in its neutralconfiguration free from external deformation force. As such, the tube 42in its neutral configuration has a first or distal portion D free fromcontact with the distal tip electrode 21, and a second or proximalportion P generally in circumferential contact with the distal tipelectrode 21. The proximal open end 44 of the tube 42 extends around theproximal end of shell wall 23 of the distal tip electrode 21 and iswrapped around and secured to the shell wall 23 by one or more bands 49(see FIG. 2A). Affixed in this manner, the tube 42 is in direct,electrically-conductive contact with shell wall 23 such thatenergization of the shell wall 23 also energizes the tube 42. Moreover,because the tube 42 is resilient, its distal portion D readilycompresses down to a size not greater than the width or french size ofthe distal tip electrode 21 and distal tip section 12 when the catheteris inserted into the patient's vasculature, for example, via a guidingsheath (not shown), and readily resumes its neutral configuration whendeployed from the guiding sheath.

In some embodiments, the tube 42 may have a uniformly cylindricalconfiguration, as shown in FIG. 5A and FIG. 5B. The tube 42, in itsneutral configuration, has a generally uniform width W1 along itslength, the width W1 being equal to or greater than the width of thedistal tip electrode 21 such that the electrode 21 may be readilyinserted into the tube 42 without significantly stretching the weave ofthe underlying material. Moreover, as shown in FIG. 5C, the distalportion D of the tube 42 expands and bulges radially from its neutralconfiguration to a width W2>W1 when distal face F of the tube 42 comesin contact with tissue upon advancement of the distal section 12 andfurther when the distal tip electrode 21 abuts or contacts tissuesurface T. With such radial expansion, the distal portion D of the tube42 enables the deformable electrode 40 to provide a larger contactsurface area or footprint F by which the tissue can be ablated comparedto that of the distal tip electrode 21 alone.

In other embodiments, the tube 42 may have a neutral configurationhaving a mushroom shape, as shown in FIG. 2B, with a distal cap portionDC and a proximal stem portion PS. The proximal stem portion PS isgenerally straight, with a generally uniform width W3 along its lengthwhere the width W3 may be generally equal to or less than the width ofthe distal tip electrode 21. The distal cap portion DC of the tube 42has a distal face DF that is generally flat or having a lesser curvatureC1, and a bulbous portion B having a greater curvature C2 that iscontinuous and thus free of any corners or sharp transitions. A width W4of the bulbous portion B is at least about 1.5 times the width W3 of thestem portion PS. When mounted on the distal section 12, the proximalstem portion PS is generally in circumferential contact with the distaltip electrode 21 and the distal cap portion DC is free from contact withthe distal tip electrode 21, as shown in FIG. 2A.

When the distal face DF of the tube 42 comes in contact with tissue Tupon advancement of the distal section 12 toward the tissue, as shown inFIG. 2C, the distal cap DC including the bulbous portion B becomes moreflattened and spreads out, expanding radially for a significantlyenlarged contact surface area or footprint F compared to that of thedistal tip electrode 21. With the distal cap DC and its bulbous portionB having a continuous curvature with no sharp angles or corners, thedistal cap DC and bulbous portion B can readily keep its overall shapeduring expansion without any kinking or undesirable deformation.

For any embodiments of the present invention, the tissue contact surfacearea F can be increased by pivoting the distal section 12 about an axisperpendicular to the contact surface area (in sweeping out a conicalvolume). In this manner, peripheral portions PY of the bulbous portion Bcan also be brought into contact with additional tissue surface F′.

In operation, the distal portion D of the tube 42 of the embodimentsherein can be inflated and irrigated by fluid, e.g., a saline solutionor any other type of suitable irrigation fluid), which the irrigationmodule 52 pumps through the irrigation tubing 31 to deliver the salineto the distal tip electrode 21 where it exits through the irrigationapertures 35, thereby generating a mechanical force sufficient toinflate distal portion D of the tube 42. While the distal portion D ofthe tube 42 is inflated and pressed against endocardial tissue T, thedistal portion may better conform to the endocardial tissue T, as shownin FIG.

When deformable electrode 40 is conductive, e.g., by comprising suitablemetal strands or a conductive polymer, ablation module 50 can convey RFenergy to the deformable electrode 40 via the lead wire 37, and thedeformable electrode 40 conducts the energy to the tissue. Alternativelyor additionally, the lead wire 37 may apply the RF energy to conductivefluid (e.g., saline) delivered into the distal tip electrode 21, inwhich case the conductive solution may conduct the RF energy throughdeformable electrode 40 to the endocardial tissue.

In other embodiments, as shown in FIG. 6, the deformable electrode 40may comprise an irrigated balloon tube 90 comprising a biocompatibleflexible and elastomeric substrate 91 having an outer surface 92 onwhich one or more conductive members or surface electrodes 93 arepainted or otherwise applied, for example, as printed circuits, sputtercoatings, etc. It is understood that the substrate 91 and balloon member90 may assume any one or more of the applicable characteristicsdescribed above and/or illustrated herein for the tube 42. Where thesubstrate 91 is not woven or otherwise porous, irrigation ports 94 maybe formed in the substrate 91 for fluid transported into the interiorcavity of the 27 of the balloon member 90 to exit the balloon member 90.

In certain embodiments, a conductive material forming the surfaceelectrodes 93 is applied by a micropen or positive displacementdispensing system, as understood by one of ordinary skill in the art. Amicropen can dispense a controllable volume of paste per time, whichenables control of thickness by varying print volume, pasteconcentration, and write speed. As shown in FIG. 7, a positivedisplacement dispensing system 160 includes a pen tip 164 that is keptsubstantially perpendicular to the surface of the substrate orunderlying material. Such a system is disclosed in U.S. Pat. No.9,289,141, titled “Apparatus and Methods for the Measurement of CardiacOutput.” Positive displacement dispensing technologies and direct-writedeposition tools including aerosol jets and automated syringes areavailable under the mark MICROPEN by MicroPen Technologies and Ohmcraft,Inc., both of Honeoye Falls, N.Y.

As shown in FIG. 7, the balloon member 90 is at least partially inflatedprior to printing the electrodes 93 on its outer surface 92. Aprocessing system, such as a computer 162, generates a contour image mapshowing the contours of the balloon member 90. Information from thecontour map obtained above is provided to the positive displacementdispensing system 160 capable of responding to the contour map byaltering one or more printing dimensions. In some embodiments, thepositive displacement dispensing system 160 contains a writing head 164(such as a pen tip) and a substrate stage 166 capable of moving theballoon member 93 in at least three independent dimensions. The writinghead is 164 capable of movement relative to the substrate stage 166. Thewriting head 164 applies to the substrate any liquid or semi-solidmaterials, and the conductive material used to form the electrode(s) 93.

The writing head 164 is mounted on an axis capable of moving in onedimension only, shown in FIG. 7 as the y-axis. In contrast, thesubstrate stage 166 capable of moving in at least three independentdimensions: the x-axis, .phi. (clockwise or counter-clockwise rotationalong the z-axis, and .theta. (clockwise or counter-clockwise rotationalong the x-axis). In certain embodiments, the substrate stage 166 iscapable of moving in a fourth independent direction, shown in FIG. 7 asthe y-axis.

The surface electrodes 93 may assume any variety of patterns on theballoon member 90. One or more solder pads 69 (FIG. 6) may be providedto electrically connect internal lead wires 37 and the surfaceelectrodes 93. One or more lead wires 37 may transition from inside thesheath 46 to outside via aperture(s) 71 formed in the sheath 46 toconnect with the solder pad(s) 69. In other embodiments, the electrodes93 are connected to the tip electrode 21 by lead wires to conduct RFenergy. The lead wires may run along the outer surface of the balloonmember 90 to reach the tip electrode 21, or they may run through theinterior of the balloon member to reach the tip electrode 21.

In some embodiments, the balloon member 90 is constructed of aconductive polymer. In some embodiments, the balloon member 90 has abulbous or donut shape, defined as a toroidal configuration having agenerally circular cross-section, and a center opening through which thedistal tip electrode 21 extends, as shown in FIG. 8A and FIG. 8B. Insome embodiments, the balloon member 90 has a width W ranging betweenabout 4.0 mm and 5.1 mm. As shown in FIG. 8B, the balloon member 90,when inflated, presents a distal surface in the shape of a ring forcontact with tissue surface.

The preceding description has been presented with reference to presentlydisclosed embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale, and any feature or combinationsof features described in some embodiments may be incorporated into anyother embodiments or combined with any other feature(s) of anotherembodiment, as desired or needed. Accordingly, the foregoing descriptionshould not be read as pertaining only to the precise structuresdescribed and illustrated in the accompanying drawings, but rathershould be read consistent with and as support to the following claimswhich are to have their fullest and fair scope.

What is claimed is:
 1. A catheter probe, comprising: a flexibleelongated shaft; a distal section having a distal tip end, and anelastically deformable electrode configured to adopt a neutralconfiguration and a tissue contact configuration, the deformableelectrode comprising a hollow porous tube with a distal portion having aclosed distal end, and a proximal portion defining an opening to aninterior of the tube, the distal tip end received in the tube throughthe opening and the distal section generally surrounded by tube; whereinthe closed distal end of the tube is spaced apart from the distal tipend and the distal portion of the tube has a lesser width W1 when thedeformable electrode is in the neutral configuration, and wherein thedistal portion of the tube has a greater width W2 when the deformableelectrode is in the tissue contact configuration.
 2. The catheter probeof claim 1, wherein the distal portion has a preshaped bulbousconfiguration.
 3. The catheter probe of claim 1, wherein the preshapedbulbous configuration has a continuous curvature.
 4. The catheter probeof claim 1, wherein the greater width W2 is at least about 1.5 timesgreater than the lesser width W1.
 5. The catheter probe of claim 1,wherein the tube is porous.
 6. The catheter probe of claim 1, whereinthe tube includes woven material.
 7. The catheter probe of claim 1,wherein the tube includes woven, electrically conducting fibers.
 8. Thecatheter probe of claim 1, wherein the tube includes biocompatibleelastomeric material.
 9. The catheter probe of claim 1, wherein the tubeincludes conductive elastomeric material.
 10. The catheter probe ofclaim 1, wherein the elastically deformable electrode includes a surfaceelectrode.
 11. The catheter probe of claim 10, wherein the surfaceelectrode includes conductive ink electrode.
 12. The catheter probe ofclaim 10, wherein the surface electrode includes printed circuitelectrode.
 13. The catheter probe of claim 10, wherein the surfaceelectrode includes sputter coating electrode.
 14. A catheter probe,comprising: a flexible elongated shaft; a distal section having a distaltip electrode, and an elastically deformable tube of woven fibers,wherein the deformable tube is configured to adopt (i) a neutralconfiguration having a preformed bulbous portion with a first width and(ii) a tissue contact configuration wherein the bulbous portion deformsinto a second width greater than the first width; wherein the bulbousportion is free from contact with the distal tip electrode when thedeformable tube is in the neutral configuration, and the bulbous portionis in contact with the distal tip electrode when the deformable tube isin the tissue contact configuration, wherein the deformable tube has aclosed distal end comprising converging fibers and an open end definingan opening receiving the distal tip electrode, and wherein thedeformable tube is electrically connected to an ablation energy source15. The catheter probe of claim 14, wherein the bulbous portion has acontinuous curvature when the deformable tube is in the neutralconfiguration and the tissue contact configuration.
 16. The catheterprobe of claim 14, wherein the tube is porous.
 17. The catheter probe ofclaim 14, wherein the tube includes woven material.
 18. The catheterprobe of claim 14, wherein the tube includes woven, electricallyconducting fibers.
 19. The catheter probe of claim 14, wherein the tubehas a toroidal configuration.
 20. The catheter probe of claim 14,wherein the tube includes a surface electrode.